1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly, to a method for manufacturing a semiconductor device that reduces or prevents copper contamination.
2. Discussion of the Related Art
Typically in performing a copper-related process such as a copper line formation as part of a back end-of-line process, a rear surface of a substrate can be contaminated with copper. That is, since copper exhibits great diffusivity in certain materials such as single-crystal silicon, copper particles penetrating through the rear surface of the substrate may be diffused to a front surface of the substrate. Various methods for removing the copper from the rear surface of the substrate are proposed.
In manufacturing a contemporary semiconductor device, a layer of silicon nitride is generally deposited on the front surface of the substrate by plasma-enhanced chemical vapor deposition. The layer of silicon nitride may serve as etch stop layer in forming a via-hole from a first line(or first level of metallization) to an underlying, silicon-based device structure (e.g., a gate, source or drain of a transistor). The nitride layer is generally not formed on the rear surface of the substrate. In addition, multi-layer spacers are generally formed in the reverse order of the deposition of the corresponding layers. Thus, since a tetraethylorthosilicate-based oxide layer may be exposed during spacer and/or copper line formation, it can be difficult to prevent the contamination of copper.